Either a name, traditionally of an old wizard but is an uncommon but still used forename, or something can be described as being merlin, replacing the outdated "cool"/"sick"/"wicked"/"awesome".
Friend of Merlin: "Hey Merlin."

Someone does something amazing.
Onlookers: Fuck man, that was merlin!
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a wizard with a long beard and a pointy hat with stars on it
not to be confused with 'Gandalf the grey', like i did, around lots of people. in the movies IT JUST GETS WORSE
by Kimmy Booth January 19, 2005
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When you take a girls long hair, hold it below her chin to form a beard, and proceed to fuck her face!
I gave the girl a Merlin!
by Mikeymc6 April 14, 2019
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A merlin (or merlyn) derived from the Middle English colloquialism for Falco columbarius, a small, bald falcon, a merlin is a vulgar maneuver, most often delivered from above--hence, the word's avian origins.

While not necessarily practiced--much like counterparts "the Cleavland steamer" and "space docking"--it has evolved into both urban myth and popular in-joke among groups of friends. There is much debate on what the act entails, often falling into regional categories. Thus, in common parlance it has become a stand-in for all bizarre, deviant and lascivious intimacies: a sort of profane catch-all, or ribald signifier, whereas what is signified is fluid and varies greatly with person and context.

The etymology of the merlin is also disputed, with some cultures ascribing it to the wizard, Merlin, of Arthurian Legend. This may be on account of the obscure and mysterious nature of the term and what it may, or may not, imply. The word can be found in literature dating as far back as the 16th century.

Currently, the growing reemergence and popularity of the term has lead, perhaps indirectly, to a decline in the popularity of its use as a given name.
be careful today. i have a feeling elizabeth's going to try to give you a merlin when you're sleeping.
by Robert de Boron August 7, 2010
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A birth defect in which the recipient possesses small, baby-like arms that resemble a poker and a lobster claw; often the result of a mother smoking crack while pregnant.
Steeler: Look at that kid, he's got the merlins!
Kevin: Don't say that!
Steeler: Nah it's okay, the kid's a dick anyway.
by lookatem69 November 16, 2009
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Merlin is sometimes used to replace words such as sperm, cum, semen, jizz and spunk. Merlin is a male gamete or reproductive cell that is produced in the testicles. The word 'merlin' is a slang word that originated in the UK.
1. She was giving me a blowjob when I pulled out and covered her face in merlin.

2. When she walked out of the toilet, she had merlin on her lip.
by Merlin maker April 1, 2013
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The founding father of Western dragonology, Merlin, or Emrys, was also a magician of some passing note.
The great and powerful dragonologist Merlin is cool.
by The Isbey August 20, 2006
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